1. Field of the Invention
This invention relates to a method that is synergistically unique for extracting valuable minerals and precious metals from ore bodies, such as oil sands ore bodies and other related ore bodies, and which is environmentally acceptable and economical.
2. Description of the Prior Art
Oil sand ore bodies, also frequently referred to as tar sands ore bodies, commonly include valuable minerals and precious metals, e.g. oil, alumina, titanium, gold, silver, platinum, etc. The oil sands ore bodies commonly include overburden material near the surface overlaying oil sands ore which have interburden clay/fines lenses interspersed throughout the oils sands ore. All of these materials have been found to contain various quantities of valuable minerals and precious metals. The overburden material and the interburden clay/fines lenses must be mined to access the oil sands ore for oil extraction. The overburden material and the interburden clay/fines lenses are hereinafter called mineral ores. Oil extraction from the oil sands ore is required for valuable minerals and precious metals recovery from the clean oil sands ore tailings.
Other related ore bodies containing clay/fines lenses frequently have similar mineralization of aluminum values with iron and titanium and possibly precious metal values. These other related ore bodies, though similar in geological and mineralogical character to oil sands ore bodies, contain little, if any, of the hydrocarbons of conventional oil, heavy oil, kerogen or bitumen.
Oil sands ore bodies and other related ore bodies are extensive worldwide and found on all major continents. Estimated potential daily oil production from oil sands ore bodies is millions of barrels of synthetic crude oil and large quantities of valuable minerals and precious metals. One of the world's major oil sands ore bodies is in Athabasca, Northern Alberta, Canada. Currently, production from these ore bodies is over 200,000 barrels per day of synthetic crude oil. The known reserves are capable of sustaining a production several times that amount throughout the twenty-first century.
Solid waste tailings generated from the recovery of oil from such oil sands ore bodies would be millions of tons per year. Approximately two tons of solid waste tailings from oil sands extraction processes are produced per barrel of synthetic crude oil. The solid waste tailings from the Canadian production of synthetic crude oil are known to contain a significant amount of valuable minerals and also additional amounts of precious metals. Past efforts to recover these valuable minerals and precious metals were directed to processing the waste tailings from the existing production of oil by a hot water process or modifications thereof. These efforts have produced limited results and have not eliminated the environmental problem of large tailings ponds. There are several methods of recovering minerals from the waste tailings produced by the hot water process as disclosed in U.S. Pat. No. 4,225,422, by Lloyd, et al; U.S. Pat. No. 4,138,467, by Kamisky, et al; and by U.S. Pat. No. 3,990,885, by Baillie, et al. The economics of these efforts have floundered because of the emulsified nature of the waste tailings which include oil, clay, solvent, water and caustic discharged as waste into the tailings ponds. Another oil extraction process as disclosed in U.S. Pat. No. 4,875,998, by Rendall and/or other known processes will provide the necessary feed stock to which this method applies.
Oil sands ore bodies and other related ore bodies as referred to herein commonly contain clays having alumina, iron and/or titanium values. U.S. Pat. No. 3,143,392, to Saeman; U.S. Pat. No. 2,951,743, to Kretzschmar; and U.S. Pat. No. 2,958,580, to Loevenstein have addressed the issue of alumina and iron extraction while discharging the titanium minerals as waste. These processes have significant drawbacks such as solid/liquid separation problems, iron impurities in the products, waste streams causing effluent disposal problems, and high energy costs. The titanium values from oil sands ore bodies and other related ore bodies may be produced through various methods, such as chlorinating processes as stated in U.S. Pat. No. 4,119,697, by Tolley; U.S. Pat. No. 3,977,863, by Glaeser; U.S. Pat. No. 3,903,239, by Berkovich; U.S. Pat. No. 3,859,077, by Othmar; and U.S. Pat. No. 3,549,322, by Klein.
The chlorinating process has advantages, such as ease of separating iron and titanium. However, it also has drawbacks, one of which is the requirement of large particle size for processing. This makes such process unattractive for the sequence of processing encountered by the present method, because it would only be suitable for partial minerals recovery. Further, heretofore, the mineral ores in oil sands ore bodies and other related ore bodies have not been utilized for economical removal of known mineral values and/or precious metal values.
A requirement exists for an extraction sequence which processes ores from these ore bodies and extracts minerals and/or precious metals economically and in an environmentally acceptable manner. For example, removal of minerals by agglomerating (pugmilling) with sulphuric acid is presently practiced on a large scale by the copper industry, as is the removal of titanium from sulphuric acid leach liquors containing large amounts of iron. Oil sands ore bodies and other related ore bodies frequently contain humic acids which resulted from the humus materials contained in the ore bodies. The chemical interaction of the humic acids with the elemental molecular matrix of the valuable minerals over long periods of geological time has enabled the agglomeration of these valuable minerals into leachable sulphates. Leaching out precious metals using various leachants such as, but not limited to, sodium cyanide is also routinely practiced on suitable ore bodies. The use of the sulphuric acid process is advantageous because SO.sub.2 can be readily recycled and the minerals are produced by proven technologies providing high yields with acceptable product quality for the market. The purification stages of alumina, titanium and iron produce SO.sub.2 which is recovered, converted into sulphuric acid and recycled as part of the overall process arrangement.